The present invention relates to a device for rapidly transferring current to an inductive load.
As is generally known, high-power current often needs to be transferred in as short a time as possible to inductive elements, e.g. for controlling high-speed electrovalves and solenoids on electrically controlled Diesel injection systems.
At present, rapid transfer of high-power current to inductive elements is performed using devices the operating principle of which substantially consists in charging a condenser with high voltage via a converter supplied with low d.c. voltage. Thus, charged, the condenser is connected to the inductive load via a switch, for supplying the required current to the said inductive load. The drawbacks of such devices mainly derive from the fact that a fairly high voltage (substantially ranging from 100 to 200 V) must be maintained at the condenser terminals, and that the amount of current required by the load demands a relatively high-capacity condenser, which, in turn, results in cumbersome size of both the condenser and the device as a whole. Furthermore, for rapidly cutting off current supply to the load, the characteristics required of the said condensers are fairly stringent in terms of internal impedance, reliability and operating temperature, all of which make for high manufacturing cost. A further drawback lies in the formation of overvoltages at the terminals of the switch, which must therefore be suitably protected, e.g. by installing a parallel-connected Zener diode. If such is the case, however, a considerable amount of power is dissipated, should operating conditions require repeat control of the inductive load at fairly high frequency.